CVE-2000-0306 in OpenServer
Summary
by MITRE
Buffer overflow in calserver in SCO OpenServer allows remote attackers to gain root access via a long message.
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Analysis
by VulDB Data Team • 01/13/2025
The vulnerability identified as CVE-2000-0306 represents a critical buffer overflow flaw within the calserver component of SCO OpenServer operating system. This issue manifests in the calendar server service that handles remote communication for scheduling functions. The flaw occurs when the server processes incoming messages without proper bounds checking, allowing maliciously crafted input to overflow allocated buffer space. The vulnerability specifically affects the calserver daemon which operates on network ports to receive calendar-related commands from remote clients. When a remote attacker sends a specially crafted message containing excessive data, the buffer overflow condition triggers, potentially allowing arbitrary code execution with elevated privileges.
This buffer overflow vulnerability directly maps to CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The flaw enables remote code execution with root privileges, making it particularly dangerous for networked systems. The attack vector involves sending a long message to the calserver service, which then fails to validate the input length before copying data into fixed-size buffers. The technical implementation of this vulnerability exploits the lack of proper input sanitization and memory management practices within the server application.
The operational impact of CVE-2000-0306 extends beyond simple privilege escalation to encompass complete system compromise. Remote attackers can leverage this vulnerability to execute arbitrary commands with the highest system privileges, effectively gaining root access to affected SCO OpenServer systems. This access enables attackers to modify system files, install malicious software, create new user accounts, and establish persistent backdoors. The vulnerability affects all versions of SCO OpenServer that include the vulnerable calserver component, making it particularly concerning for organizations running legacy systems. The attack can be executed without authentication requirements, making it especially dangerous in environments where the service is exposed to untrusted networks.
Mitigation strategies for this vulnerability require immediate patching of the affected SCO OpenServer systems through official security updates provided by SCO. Organizations should disable or restrict access to the calserver service when not required, implementing firewall rules to block incoming connections on the affected ports. Network segmentation and access control measures can help reduce the attack surface by limiting exposure to the vulnerable service. System administrators should implement monitoring for unusual network traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of input validation and proper memory management practices, aligning with ATT&CK technique T1059 for command and script injection. Regular security assessments and vulnerability scanning should be conducted to identify similar buffer overflow conditions in other system components. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability pattern.